Translating device



March -.3,- 1931*. J. s. HIGH TRANSLATING DEVICE i Filed oet. 2o, 1927 ZH INVENTOR Patented Mar. 3, l1931V UN 11T-,ED STA TES-f .Tonarm s. nien-,orvvrmz'riv'sizione.,Y rENNsYLvA'niA, .As'srGNon To wEsTinGHoUsn ELECTRIC GMANUFACTURING COMPANY; e ConronATIoN-orrENNsYLvANIA p v "TBANSLATING DEVICE Appiieatonmed october 2o, .1927. seiai No. 227,409; f

i My 'invention 2relatesf to translating' devices, and it'has particular relation to devices of the type now commonly known as loud speakers, t 'Y 'l 'E5 It has been establishedby.l previous workers in the art that improved results may be obtained from loud speakers ofthe type uti- Y *diaphragmto Vthe front thereof may readily lizing` largeconical orV plane d iaphragms if means are provided tolpreventjair Vfrom cire c ulating between the'front and the rear of the diaphragm at low frequencies. 'Such means may. take the form4 of a baifleencircling the diaphragm, as shown in thepatent to Rice, No. 1,631,646, or the rear of the diaphragm may be located in a substantially closed chamber or a chamberfllledlwithfa damping'material, such as fehlt. or Ythe like.

In the event that the loud speaker is a constituent part of a radio receiving set of the console type, a wall o-f the cabinet may conveniently-be utilized as the baflle. ,When

Vit is desiredA to construct a small, self-contained loud speaker,` however, it is inconv venient to surround `the diaphragm-housing z5 by a baliie of sufficiently large diameter to accomplish any useful purpose, and this inconvenience is accentuated if the loud speaker isof the small type designed to be suspended from the wall of a room.

It is, accordingly, an object of my invention to provide a loud speakeriwith self-con- `tained balle elements that do not materially increase the space occupied by the apparatus when such apparatus is lmounted for ,usel Another object of my invention is to providea loud speaker incorporating baHie-fde- K valternative form thereof.

vices that effectively replace the damping materials' referred toA above; Another object ofmy invention isto pro- 49 vide a loud speaker of the wall type in which is embodied an inconspicuous baffledevice.

.Another and more specific object of my invention is to providea loud speaker comprising a baffle-device damping effect.

The bale-device that I have found most suitable for incorporation into a loudspeaker of the wall type comprises a plural ity of nested circular partitions surrounding 50. the rear face of the diaphragm, and it is so that has only a slight arranged ythat Ythe .sound .waves emanating fromthefsaid rear facefare caused to travel 'in atortuousfpath before reaching thefrort i Vof thev diaphragm and there -c'or'nmingling "v with the sound waves emanatingv therefrom. By vproperly proportioning the partitions, the lengthV ofthe path from the rear ofthe cases, to so proportion and space the baliiepartitions that the passage afforded thereby Y increases 1n area 1n a manner 'somewhat analogous Vto the increase in cross-sectional area of the Vexponential horn'disclosed in the patent to Hanna andfSlepian, No. 1,623,561, in order that the dampingimposed on the rear surfacev of the diaphragm shall belargej y ly independent of frequencyA c Among the novel features of my invention are those particularly set forth inthe appended claims. The invention itself, however, both as to its organization and vits method of operation, together with further objects and advantages thereof, willbest beV understood from a consideration of the following description of certain specific embodi-r ments, vtaken in oonnectionwith Athe -accompanying drawings, in which v 'Y e Figures 1 and 2` are cross-sectional and,V front elevational views, respectively, of a preferred embodiment 'of my invention, and

Figs. 3 and ly are analogous views of anl a wall 4. In lieu of the bolts 3, the device may, if desired, be provided withany other convenient suspension means.

A iA 'circular coverv plate 5, which maybe flat orconcaved toward the-center, as shown, is mounted inspaced, parallel relation `to the base plate 1, themounting means therefor comprisinga plurality of spacing devices 6,

each providedrwith an nternally'threaded opening into the opposite ends of which eX- tend bolt-s 7 and 8 that project through counytersunk holes provided in the plates 1 and 5.

A large central opening is provided in the cover plate, in order to accommodate a diaphragin 10, which is freely suspended therein from an annulus 11 of velvet, kid, rubber,

or equivalent material. The outer edge, of the annulus 11 is clamped between theV cover plate,V and a pressure-ring 12, a plurality of screws 13 serving to maintain the ring in position.

In order to actuate the diaphragm,` an" electromagnetic driving ldevice 14 is provided. This'device, which may be of any conventional type, is mounted `on the. base plate l, and is operatively connected to the ldiaphragm by means of a flexible-connector j inwardly from the cover plate to within a short distance from the inner surface of the A'base plaftel. Additional circular partitions 17 project yfrom the base plate ,to within a short distance from the inner face of the cover plate 5', the partitions carried by each plate alternating radially of the device to define a tortuous sound-passage that repeatedly bends back on itself. i f

The sound passage, which is indicated by the arrows, may be given any rdesired length and rate of expansion by properly choosing the number and spacing of the partitions, or baffles 16 and 17. Preferably',` the total length of the path from the center of the inner face of the diaphragm to the center of the outer. face thereof is made equalto a quarter wave-length of the lowest sound frequency it is intended to reproduce. The mathematical basis for this statement is given to the Rice patent previously referred to and need not be repeated here. It is sufficient te say that, by preventing a free circulation of air between the rear and the front of the diaphragm, the response thereof to low frequencies' is greatly improved, and the ethciency of the device is increased.

Although I have shown in the drawing only two such partitions carried by the base and two carried by the cover, it lies within the scope of my invention to provide as many of such partitions as are necessary.

`The bailes 16 and 17 have also lan addif tional important function of preventing the diaphragm housing from resonating at any particular frequency. Such resonance effects have, in the past, seriously yinterfered with the `quality of musicrreproduced by loud the baille-partitions are so arranged that thev sound passage froml the rear of the diaphragm tov the open air progressively Vincreases in vareafrom the center of the diaj phragm radially outward. Theincrease in area. is preferably approximately exponential in character, and the sound passage Vaccordingly tends to damp or `load the diaphragm to substantially the sainev amount, irrespective of frequency, provided the ,velocity of the diaphragm is maintained a constant.

Y The modification of my invention inrwhich the sound passage is so arranged that it pirogressivelyincreases in area, is illustrated in Figs. 3 and 4 and comprises a base 20, which supports, through the agency of aplurality ofspacing devices 2l, al cover 22 having a larfre central opening. An annular element 23 is supported' from the inner surface of the cover 22, and cooperates with thebase to define a circular sound opening that increases exponentially. A conical diaphragm is freely suspended in the opening ironia resilient annulus 24 which is 4held concentric with the opening by a clamping ring 25.' A loud-speaker motorV 27, of any conventional type, is affixed tothe base member 29 and is operatively connected to the apeX of the diaphragm.

VA plurality ofv circular partitions 28 surround tlie driving motor 27, the radial distance between successive partitions increasing toward the periphery of the device. These partitions increase in height progressively, the free edges thereof being arranged to lie in the surface ofan imaginary cone which has, at its apex, a slightly more obtuse anglethan the apex of the cone diaphra vThecover plate is provided also wit a Vplurality of concentric depending partitions 29 which are arranged in nested relation to aplurality of additional partitions 30 carried bythe base member, the radial distance between adjacent partitions increasing toward the periphery-of the device, considered as a. whole. v

The sound passage, therefore, defined by the several baille devices, is somewhat obstructed in the vicinity of the-,rear of the diaphragm by the bailes 28, and the peripheral portion thereof is rendered tortuous by the interleaved or nested relation of the additionalpartition members 29 and 30. The pro- `visio-i1 of the artition members 28 directly to the rear o the diaphragmis-important in preventing resonance yeffects from the enclosure while, at the same time,the'passage of the sound to the exterio-r ofthe device is but slightly hampered thereby. l

By reason ofthe increased spacing between successive partitions, the sound passage may be given any desired. rate o-f cross-sectional increase. In the example illustrated, it will be noted that any radial element of the Vpassage, as defined b-y the partitions, increases in area from the center, of the peripheral outlet. Although this increase in area is not smooth, as is the case in the exponential horn disclosed in the Slepian et al. patent previously referred to,yet, at thev same time, it may be made to approximate the rate of increase shown in that patent.

The sound passage may be given any del sired length by properly choosing the number and spacing of the baffle partitions, as explained in connection with Fig. 1. This length is preferably also made approximately that of a quarter wave length of the longf est sound wave it is desired to produce.

A loud speaker, constructed according to my invention, is'considerably more efficient than loud speakers ofthe type wherein the.

diaphragm is exposed freely to air `on both sides thereof and is also more 'eicient than loud speakers wherein thek rear surface of the diaphragm is 4enclosed by a chamber provided with damping means, such as felt or the like. The load imposed on the diaphragm by Va housing constructed according to my invention is quite even over a wide range of frequencies, and pronounced resonance effects are noticeably absent.

I have described my invention as being particularly useful in connection with cone or plane diaphragins of large area but it is not restricted to use therewith, being applicableto loud speakers of the type wherein a small metallic diaphragm is directly actuated by electromagnetic means.V

It is also entirely feasible to incorporate my invention into a small table, in which' event the base-plate l shown in Fig. l, may

constitute the table-top. This'modilication, being sufliciently obvious, is not illustrated.

Although I have illustrated only two specific embodiments of my invention,.numerous modifications thereof will be apparent to those skilled in the art. My invention, therefore, is not to be limited except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim as my invention:

l. In a sound-producing device, a diaphragm, means for actuating said diaphragm, and bale means offering a tortuous path to sound waves emanating from the rear surface of said diaphragm.

2. In a sound-producing device, Va diaphragm, actuatingmeans=therefor,'and`a pluv ralityf of baie-delvices'interposed ina'path j traveled by sound=wavesbetween the front and the rear surfaces of said Vdiaphragm'. In "asound-producingdevice, va diaphragm, actuating means for said diaphragm,

and aplurality of bailie-devicessurrounding Y therearsurface of said diaphragm, said baille idevices cooperating -to'` delinea `tort'uous sound-p-assagerfrorn the rear surface tothe front-surface ofsaiddiaphragm.

4, In `a soundproducing device, al diay phragm, actuating mea-ns for said diaphragm, and a pluralit of baffle-devices surrounding -the rear of sai diaphragm, saidbaffle-devices cooperating to delinea sound passage'vof gradually increasing area.

5.7In a sound-producing device, a diaphragm, actuating means for said diaphragm, V

and a plurality of baffle-devices surrounding the rear-of said diaphragm, said baliie devices cooperating to define a tortuous sound passage having an approximately exponential v V v increase in area.

6; In a sound-producing device, a diaphragm actuating means for said diaphragm, and a plurality of halide-devices surrounding the rear of said diaphragm, said baiiie-devices cooperatingto define atortuous sound passage having a length Vat least approximately equal to one quarter Vwave length of the lon-gest useful sound wave to be producedl thereby. Y V l 7. In a sound-producing device, a diaphragm,- actuating means for saiddiaphragm, y and a plurality of baffle devices surrounding the rear of said diaphragm, said baiiie-de-v vices comprising concentric partitions.'

8.,In a sound-producing device, a substantially freely suspended diaphragm, and a plurality of concentric balile devices associated with the rear of said diaphragm, certain of said baHie-devices being arranged in nested relation to define a tortuous soundpassage.

k9. Ina sound-producing device, a base, a

' diaphragm-mounting element, a substantially freely-movable diaphragm mounted on said element, and a plurality of concentric fine a tortuous sound' passage.

' 11. In a translating device, a diaphragm,

a plate support for the -edge'portion of-said diaphragm, ,andra mounting device for said plate support, vsaid plate support.v `being v curved outwardly with hreference tov said mounting device to define anrair passageway rearwardly of said diaphragm that increases in area approximately exponentially.

: In testimony whereof, I have hereunto subscribed my name-this 5th da-y of October,

JUR-JVEN s.V HIGH. 

